首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   153篇
  免费   1篇
化学工业   36篇
金属工艺   2篇
机械仪表   1篇
建筑科学   3篇
矿业工程   1篇
轻工业   11篇
武器工业   1篇
无线电   17篇
一般工业技术   14篇
冶金工业   41篇
自动化技术   27篇
  2023年   1篇
  2021年   4篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2014年   6篇
  2013年   5篇
  2012年   3篇
  2011年   8篇
  2010年   10篇
  2009年   9篇
  2008年   10篇
  2007年   13篇
  2006年   4篇
  2005年   5篇
  2004年   11篇
  2003年   7篇
  2002年   6篇
  2001年   1篇
  2000年   1篇
  1999年   4篇
  1998年   5篇
  1997年   8篇
  1996年   6篇
  1995年   5篇
  1994年   3篇
  1993年   1篇
  1991年   2篇
  1990年   1篇
  1981年   3篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
排序方式: 共有154条查询结果,搜索用时 15 毫秒
1.
The state of Oregon decided to cover all potentially eligible Medicaid citizens to 100% of poverty. Previously, Oregon had covered persons up to 67% of poverty. In order to keep overall program costs in check. Oregon decided to limit the number of services that its Medicaid program would cover. Oregon's normative choice was to contain program costs by covering all eligible persons up to 100% of poverty, while at the same time uniformly limiting access to certain services for everyone in the overall group of eligible persons. The state developed a prioritization list of medical services and priced the components on the list. The amount of money ultimately available for the Medicaid program was a political decision informed by data about the cost of different services and influenced by the priorities set through an independent process of priority-setting. Physicians were asked to determine what works medically, how well it works, and what benefits accrue to patients. Recognizing that physician perspectives on efficacy might vary from patients' perspectives on valuation of benefits, Oregon's planners developed a method for valuing medical outcomes that stemmed from particular medical interventions. This blend of medical fact and value to patients allowed for comparing valuations by introducing cost considerations. Condition-treatment (CT) pairs linked a medical condition with one or more courses of treatment. The goal was to determine the likely incremental medical benefit from a given treatment. In addition, Oregon developed a Quality-of-Well-Being scale to determine the net patient benefit from medical intervention and used a telephone survey to value that net benefit. A cost-benefit ratio was derived, and a prioritization of CT pairs was developed. The article analyzes and evaluates Oregon's use of cost-benefit calculations in the allocation of Medicaid funds, noting that Oregon itself backed away from many of the implications of its cost-benefit analysis and that the Americans with Disabilities Act has constrained use of quality-of-life judgments in Medicaid resource allocation decision-making.  相似文献   
2.
The differential transform method (DTM) is an analytical and numerical method for solving a wide variety of differential equations and usually gets the solution in a series form. In this paper, we propose a reliable new algorithm of DTM, namely multi-step DTM, which will increase the interval of convergence for the series solution. The multi-step DTM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions for systems of differential equations. This new algorithm is applied to Lotka–Volterra, Chen and Lorenz systems. Then, a comparative study between the new algorithm, multi-step DTM, classical DTM and the classical Runge–Kutta method is presented. The results demonstrate reliability and efficiency of the algorithm developed.  相似文献   
3.
Contextual information, such as color and spatial location, has been found to be better remembered for emotional than for neutral items. The current study examined whether the influence of emotion extends to memory for another fundamental feature of episodic memory: temporal information. Results from a list-discrimination paradigm showed that (a) item memory was enhanced for both negative and positive pictures compared with neutral ones and was better for negative than for positive pictures and (b) temporal information was better remembered for negative than for positive and neutral pictures, whereas positive and neutral pictures did not differ from each other. These findings are discussed in relation to the processes involved in memory for temporal information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
4.
The synthesis of new organic hole transporting materials (HTMs) based on 3,6‐disubstituted 9H‐carbazole‐3,6‐diamine,N,N,N′,N′‐tetraphenyl‐9‐(4‐methoxyphenyl) derivatives and their applications in solid state dye sensitizer solar cells (DSSCs) are described. The effect of the methoxy group localized on the para position of the diphenylamine moieties on the thermal, electronic and electrochemical properties and photovoltaic performance is discussed. In solid state DSSCs, utilization of the aforementioned HTMs in combination with the dye D102 (TiO2/D102/HTM/Au) shows a positive influence of the methoxy group on the photovoltaic conversion efficiency compared with unsubstituted diphenylamine grafted groups. A study on the concentration of the HTM is also carried out and shows an optimal concentration around 200 mg mL?1. Without further optimization, the best device gives a power conversion efficiency of 1.75% under AM 1.5 solar irradiation (100 mW cm?2).  相似文献   
5.
In this study, the outcome of operating conditions of extrusion assisted by supercritical CO2 for the manufacture of poly(lactic acid) foams was investigated. It was found that the temperature before and inside the die was the most prominent parameter to tune the foam properties. Foam porosity as high as 96% could be obtained (for die temperature between 109 and 112 °C), representing a total expansion exceeding 30. In this temperature range, low crystallinity (≈6%) was induced giving foams with high radial expansion i.e., large diameters and open porosity. At 112 °C, the CO2 was able to greatly expand the foams, providing 73% of its potential blowing effect. On the other hand, a low die temperature (below a die temperature of 107 °C) induces a significantly higher level of crystallinity resulting in foams with closed‐porosity and a large longitudinal expansion due to higher strength of the polymer melt. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45067.  相似文献   
6.
The synthesis and properties of glass-forming diphenylamino-substituted derivatives of 9-phenylcarbazole with methoxy groups in the different position of diphenylamino moieties are reported. A comparative study on their thermal, optical, photoelectrical and electrochemical properties is presented. The synthesized compounds exhibit high thermal stability with 5% weight loss temperatures ranging from 344 to 475 °C. The derivatives absorb electromagnetic irradiation in the range of 225–425 nm with the band gaps of 2.94–3.08 eV. The ionization energies of the synthesized compounds range from 5.04 to 5.56 eV. The lowest ionization energies and band gaps are observed for compounds containing para methoxy-substituted phenyl rings of diphenylamino moieties and for disubstituted carbazole derivatives. Charge-transporting properties of the selected compounds were tested by time-of-flight technique. Hole drift mobilities in the amorphous layers of the materials reach 10−3 cm2/V s at high electric fields. The derivatives were tested as hole transport materials in solid-state dye sensitized solar cells and showed conversion efficiency up to 0.54%.  相似文献   
7.
Although formerly considered an intermediate product, packaging has become a main component of the product and largely contributes to its perceived quality. It is the first contact with consumer. For many years, the food industry has used sensory analysis techniques to improve the gustative and olfactive quality of its products, yet there has been very little application to the packaging. The present article investigates issues involved in the recruitment and training of a sensory tactile expert panel for beverage packaging. The study addresses two important questions: what are the sensory tactile attributes that are usable for packages, and do the hand movements performed by each expert have an impact on the sensory response? The first part presents the research of sensory attributes and the training of two groups on different types of beverage packaging (glass, plastic, aluminum bottles). The performances of both groups have been controlled. In the second part, the impact of hand movements (kind of movement, variation, and strategy of haptic exploration) is demonstrated by a three-step experiment.  相似文献   
8.
The surface properties of two perfluoroalkylethyl acrylic copolymers—aqueous, Zonyl®329 and solvent‐based, Zonyl®225—were studied. Zonyl®329 is a water‐based dispersion and Zonyl®225 a solvent‐based copolymer solution; both polymers have the same perfluoroalkyethyl side chains [F(CF2)nCH2CH2? ] but have different comonomer compositions. Thin films, prepared by dip coating onto mica and quartz, with and without annealing, were characterized by contact angle and by X‐ray photoelectron spectroscopy (XPS). The contact angle measurements showed little variation with polymer and with substrate, consistent with the supposition that the perfluoroalkylethyl chains aggregate on the surface and thus dominate surface properties, irrespective of the composition of the rest of the polymer. XPS revealed only small variations in surface chemistry for studied films. Annealed films showed improved segregation for solvent‐based Zonyl®225, which has both hydrocarbon alkyl and perfluoroalkylethyl side chains; the presence of hydrocarbon alkyl chains enables the perfluoroalkylethyl chains to reorganize after annealing. Depending on the external conditions, this thermal treatment can enable more perfluoroalkylethyl chains to reach the film surface (solid/air interface), leading to a reduction in the dispersive‐dominant surface and enhancement in perfluoroalkylethyl segregation. This suggested that perfluoroalkylethyl side chains dominate the surface properties, which are thus not dependent on substrate, backbone composition, or formulation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   
9.
The tetrapeptide Ala-lle-Gly-Met bound to a Wang resin via the methionine residue was studied by NMR under MAS conditions and compared to the same peptide in solution. The bound peptide exhibits average linewidths superior to those observed for the peptide in solution. The origin of the residual NMR linewidth observed for the bound form was investigated. The dynamics of the peptide is shown to be only marginally responsible for the increased linewidth; the major cause of the line broadening appears to be nonaveraged magnetic susceptibility differences.  相似文献   
10.
The fatty acid (FA) composition of food is requested for labelling purposes and food composition tables. Suitable analytical methods for labelling purposes must be able to efficiently identify and accurately quantify FA as swiftly and cheaply as possible. This study evaluated a middle‐length highly polar column, the BPX‐70 60‐m column, to balance analysis efficiency and duration. The use of a 60‐m column led to the loss of data on minor FA but a gain in analysis time. The column was evaluated by analysing the FA composition of ten cookies made with different kinds of fats, including milk fat, and pure and/or partially hydrogenated vegetable oils. The FA elution order in this GC phase has been poorly documented in the literature compared to equivalent highly polar CPSil‐88 and SP‐2460 GC phases. Co‐elutions and overlaps on the BPX‐70 column were studied and commented upon. Overall, the BPX‐70 60‐m column could be used for rapid screening of the FA composition of simple foods. Analysis of the FA composition of a complex matrix, such as a dairy product, and specific analysis of trans‐FA required a longer highly polar column, possibly after fractionation by silver‐ion liquid chromatography. Compared to other GC phases, the BPX‐70 enabled effective isolation of 18:3 isomers although these isomers co‐eluted with 20:1 isomers on other highly polar GC phases. However, some CLA isomers co‐eluted with other FA on this column, and a specific analysis of these special FA would require another phase and/or different chromatographic conditions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号